The world could soon see the first single definition of terrorism, after appeals judges at the UN-backed Special Tribunal for Lebanon on Wednesday set a precedent for international courts, on what definition of terrorism the Lebanon tribunal will apply.

There are various definitions of terrorism in a dozen international conventions, but still no universal definition of an act of terrorism as an international crime. The Lebanon tribunal is the world's first international court with jurisdiction over the crime of terrorism. It was set up to try those accused over the 2005 assassination of the former Lebanese Prime Minister Rafiq Hariri and 22 others. The tribunal applies Lebanese law, but interprets this in the context of international law.

In a landmark ruling, judges unanimously agreed to use Lebanon's definition of terrorism as an "act intended to spread terror" - but they also agreed to apply a broader international interpretation of the 'means' of an attack - whether the weapons used were intended to endanger members of the public. The panel said that, as the tribunal must account for the "gravity of the trans-national character" of the Hariri attack, the notion of terrorism as an international crime should be considered in the context of customary international law.

The heart of the ruling lies in the difference between Articles 2 and 3 of the tribunal's statute. Article 2 is based on Lebanese law, while Article 3 relies on the norms of international law. If in doubt over which Article to choose in applying a definition of terrorism, a judge should then decide on a definition in favour of an accused. But terrorism suspects in the future, can expect tougher sentences, as terrorism could be added to a list of charges including murder and perpetration.

Presiding judge Antonio Cassese said the notion of international terrorism is in the process of being born, and that the abstract answers to questions posed by the pre-trial judge Daniel Fransen, will "need to be revisited in future trials". Fransen is now to decide whether to confirm a draft indictment submitted by prosecutors last month. The indictment, which is confidential, is expected to accuse Hezbollah members of involvement in Hariri's assassination. If the indictment is confirmed, the court could issue arrest warrants against the accused. Hezbollah denies any involvement.